There were five roads practicable for artillery piercing the _first line_ of defence, namely, two at Torres Vedras, two at Sobral, and one at Alhandra; but as two of these united again at the Cabeça, there were, in fact, only four points of passage through the _second line_, that is to say, at Mafra, Monte Chique, Bucellas, and Quintella in the flat ground. The aim and scope of all the works was to bar those passes and to strengthen the favourable fighting positions between them, without impeding the movements of the army. These objects were attained, and it is certain that the loss of the _first line_ would not have been injurious, save in reputation, because the retreat was secure upon the _second and stronger line_, and the guns of the first were all of inferior calibre, mounted on common truck carriages, and consequently immoveable and useless to the enemy. The movements of the allies were free and unfettered by the works. But the movements of the French army were impeded and cramped by the great Monte Junta, which, rising opposite the centre of the first line, sent forth a spur called the Sierra de Baragueda in a slanting direction, so close up to the heights of Torres Vedras that the narrow pass of Ruña alone separated them. As this pass was commanded by heavy redoubts, Massena was of necessity obliged to dispose his forces on one or other side of the Baragueda, and he could not transfer his army to either without danger; because the sierra, although not impassable, was difficult, and the movement, which would require time and arrangement, could always be overlooked from the Monte Agraça, whence, in a few hours, the allied forces could pour down upon the head, flank, or rear of the French while in march. And this with the utmost rapidity, because communications had been cut by the engineers to all important points of the Lines, and a system of signals were established, by which orders were transmitted from the centre to the extremities in a few minutes. Thus much I have thought fit to say respecting _the Lines_, too little for the professional reader, too much, perhaps, for a general history. But I was desirous to notice, somewhat in detail, works, more in keeping with ancient than modern military labours, partly that a just idea might be formed of the talents of the British engineers who constructed them, and partly to show that lord Wellington’s measures of defence were not, as some French military writers have supposed, dependent upon the first line. Had that been stormed, the standard of Portuguese independence could still have been securely planted amidst the rocks of the second position.